Key result
The C-terminal domain of β-coronavirus Nsp1 proteins confers high-affinity ribosome binding to inhibit translation, functioning by recruiting the N-terminal effector domain.
The study identifies the conserved mechanism by which β-coronavirus Nsp1 binds the ribosome to inhibit host translation, providing potential targets for pharmacological intervention.
Nsp1 host shutoff conservation across coronaviruses supports broad antiviral strategies; leaves open β-CoV ribosome-binding specificity for selective inhibition.
An important pathogenicity factor of SARS-CoV-2 and related coronaviruses is Nsp1, which suppresses host gene expression and stunts antiviral signaling. SARS-CoV-2 Nsp1 binds the ribosome to inhibit translation through mRNA displacement and induces degradation of host mRNAs through an unknown mechanism. Here we show that Nsp1-dependent host shutoff is conserved in diverse coronaviruses, but only Nsp1 from β-CoV inhibits translation through ribosome binding. The C-terminal domain of all β-CoV Nsp1s confers high-affinity ribosome-binding despite low sequence conservation. Modeling of interactions of four Nsp1s to the ribosome identified few absolutely conserved amino acids that, together with an overall conservation in surface charge, form the β-CoV Nsp1 ribosome-binding domain. Contrary to previous models, the Nsp1 ribosome-binding domain is an inefficient translation inhibitor. Instead, the Nsp1-CTD likely functions by recruiting Nsp1’s N-terminal “effector” domain. Finally, we show that a viral cis -acting RNA element has co-evolved to fine-tune SARS-CoV-2 Nsp1 function, but does not provide similar protection against Nsp1 from related viruses. Together, our work provides new insight into the diversity and conservation of ribosome-dependent host-shutoff functions of Nsp1, knowledge that could aide future efforts in pharmacological targeting of Nsp1 from SARS-CoV-2, but also related human-pathogenic β-coronaviruses. Our study also exemplifies how comparing highly divergent Nsp1 variants can help to dissect the different modalities of this multi-functional viral protein.
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Maurina et al. (2023) studied SARS-CoV-2 and related coronavirus infection. Nsp1 protein from β-coronaviruses was evaluated on Ribosome binding and translation inhibition. The C-terminal domain of β-coronavirus Nsp1 proteins confers high-affinity ribosome binding to inhibit translation, functioning by recruiting the N-terminal effector domain.
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